The present invention relates to eddy current separators and more particularly to such separators in which conductive particles are impelled by eddy currents generated by magnetic flux projected across the gap by rotating magnetic poles. The present invention is an improvement on the apparatus disclosed and claimed in my earlier U.S. Letters Pat. No. 3,448,857.
As distinct from magnetic separation, eddy current separation can be effective with conductive materials or particles which are not magnetic in character. Whereas magnetic separators typically operate by attracting the pieces to be separated out from a mixture, eddy current separators operate by sweeping magnetic flux through the mixture so that eddy currents are developed in any conductive particles in the mixture and these particles are subject to a resultant force. The magnitude of the resultant force is dependent on electrical resistivity, size and shape of the conductive particle, magnetic field flux strength and the velocity and frequency of the rotating magnetic poles. Thus, while similar constituent elements may be employed in separators of the two types, their actual modes of operation and the relative orientations of the elements are substantially different. A typical application for an eddy current separator in accordance with the present invention is separating aluminum cap pieces from shredded plastic bottles which are to be recycled.
Among the several objects of the present invention may be noted the provision of novel apparatus for separating conductive particles from non-conductive particles; the provision of such apparatus which is highly selective in separating conductive from non-conductive materials; the provision of such apparatus which is highly reliable and which is of relatively simple and inexpensive construction. Other objects and features will be in part apparent and in part pointed out hereinafter.